After the grinding wheel of known quick-action clamping devices for right-angle grinders has been positioned, the spindle is secured with a fork wrench or a built-in spindle stopping device; then a tension nut is positioned by hand and tightened by means of a wrench. This last step is actually superfluous. Upon activation, the spindle starts up quickly and jerkily so that, because of the mass inertia, an automatic clamping of the grinding wheel is effected by means of the tension nut. During subsequent operations the clamping device automatically tightens further.
To replace the tools, the spindle is held securely and the tension nut is loosened by means of a wrench, often with a considerable expenditure of strength. With machines that have a spindle stop, it is now possible to block the spindle abruptly, shortly before it comes to a dead stop, with the consequence that the grinding wheel rotates further because of its mass inertia, thereby loosening the tension nut. If this spindle stop is triggered at too high an rpm, the fast-running grinding wheel can screw the tension nut completely down. The still-rotating wheel can then fall off of the spindle and cause accidents and damage.
Various quick-action clamping devices for disk-shaped tools, all of which possess the described disadvantage, are known from German Published, Non-Examined Patent Applications 30 12 836, 37 00 968, 39 03 765, 39 03 767, 39 17 345, European Patent Disclosure EP 0 381 809, and International Patent Publications WO 88/04975 and WO 88/04976.